1. Technical Field
The present invention relates to an optical device, an optical scanner, and an image display device.
2. Related Art
An optical scanner which performs two-dimensional scanning with light has been known as an optical device used in, for example, a projector (for example, see JP-A-2008-216920).
For example, the optical scanner disclosed in JP-A-2008-216920 includes a frame-shaped driving member, a pair of first shaft members that supports the driving member so as to be rotatable about the X-axis, a movable plate that is provided in the driving member and includes a light reflecting portion, and a pair of second shaft members that support the movable plate so as to be rotatable about the Y-axis perpendicular to the X-axis with respect to the driving member.
The optical scanner includes a permanent magnet that is provided in the driving member, a coil that is provided opposite to the permanent magnet, and a voltage applying unit that applies a voltage to the coil. A line connecting both poles of the permanent magnet is inclined with respect to each of the X-axis and the Y-axis in a plan view.
The voltage applying unit applies a superimposed voltage of a first voltage and a second voltage with different frequencies to the coil to rotate the movable plate about the Y-axis at the frequency of the second voltage while rotating the movable plate about the X-axis at the frequency of the first voltage. In this way, it is possible to perform two-dimensional scanning with light reflected from the light reflecting portion of the movable plate.
However, in the optical scanner disclosed in JP-A-2008-216920, since the first shaft member is directly connected to the side surface of the movable plate provided with the light reflecting portion, stress is applied to the movable plate due to the torsional deformation of the first shaft member during the rotation of the movable plate and the movable plate warps. As a result, it is difficult to accurately perform scanning with light.